Acceleration of the head evokes responses from the vestibular receptors in order to compensate for head motion. This is referred to as the vestibular ocular reflex (VOR). Under normal conditions, the VOR can allow an individual to maintain visual fixation during head movement, by ensuring that for every movement of the head, there is an equal and opposite compensatory movement of the eyes. Stimulation of the vestibular receptors in the semi-circular canals can result from angular head acceleration and from stimulation of the otolith organs from linear acceleration (i.e. gravity, head tilt, and centrifugal force). These signals can activate the central nervous system through reflexes that evoke changes in the extra-ocular muscles, the visual system, and posture, enhancing acuity during head rotation and balance during changes in body position. The semicircular canals, and the signals they send to the brain, function as yoked pairs. In the absence of head motion, a train of pulses is sent from each side of the head. As the head experiences acceleration (other than gravity), the pulse train on one side of the head increases in frequency while on the other side it decreases. Our brains have adapted to interpret this differential signal as acceleration. When the central nervous system cannot balance the excitatory and inhibitory inputs from the semi-circular canals and otolith organs, the individual can experience an illusion of motion and/or loss of balance.
There has been various research into the use of galvanic vestibular stimulation in terms of simulators, directional cueing, and alleviating symptoms of motion sickness, however, there are still many needed improvements to the current technology. In particular, there is a need for a simulator system that gives a user a more realistic view of driving a vehicle such as a boat, airplane, automobile, and the like. For example, even flight simulators that use a motion platform are limited in the amount and type of motions they can impart to the user. There has also been some work in the use of GVS to alleviate feelings of motion sickness. However, the current systems use AC current to override the natural brain signals that cause a person to feel sick. This overriding requires more electrical energy being provided to a user. The use of more electrical energy can be a safety concern to a user. Therefore, there is a need for GVS technology that uses less external electrical energy on a person. Additionally, GVS technology has been applied to users causing them to physically move side to side. However, there is a need to develop this technology to be more precise and accurate as well as be able to move a person in many different directions, including forward and backward. For example, it would be advantageous to the public to be able to precisely direct a person or a group of people to a specific distinct location with the use of GVS technology.